Cathode including insulation layer on cathode tab and secondary battery including the cathode

Abstract

Provided is a cathode including a cathode current collector, a cathode tab protruding from the cathode current collector, and an insulation layer coated with an insulating material on the cathode tab, and a secondary battery including the cathode. Since the cathode of the present invention includes an insulation layer on a cathode tab, the present invention may prevent an internal short circuit which may occur due to cell deformation or sharp edges of electrodes, which are formed during cutting of the electrodes in a preparation process of the battery, when the electrodes are stacked, or may prevent a physical short circuit between the cathode and the anode due to shrinkage of a separator in a high-temperature atmosphere. In a case where the cathode is used in a lithium secondary battery, safety and reliability in battery performance may be significantly improved.

Description

TECHNICAL FIELD[0001]The present invention relates to a cathode including a cathode current collector, a cathode tab protruding from the cathode current collector, and an insulation layer coated with an insulating material on the cathode tab, and a secondary battery including the cathode.BACKGROUND ART[0002]Demand for secondary batteries as an energy source has been rapidly increased as technology development and demand with respect to mobile devices have increased, and as a result, a significant amount of research into batteries that can meet various demands has been conducted.[0003]Typically, in terms of the shape of the battery, demand for prismatic type batteries and pouch type batteries having a thin profile which may be used in products, such as mobile phones, is high, and, in terms of materials, demand for lithium secondary batteries, such as lithium cobalt polymer batteries having excellent energy density, discharge voltage, and safety, is high.[0004]One of major research pr...

AI Technical Summary

Benefits of technology

The invention aims to prevent a short circuit between the cathode and anode in a battery caused by cell deformation or shrinkage of a separator in a high-temperature atmosphere. It includes an insulation layer that is coated with an insulating material on the cathode tab to improve safety and reliability in battery performance.

Problems solved by technology

A leading cause of safety-related, incidents in batteries is attributed to the attainment of an abnormal high-temperature state due to a short circuit between a cathode and an anode.

However, there may be limitations in using a typical separator alone under abnormal misuse or abuse conditions, for example, the occurrence of overcharge or overdischarge of the battery, or dendritic growth of an electrode material or the occurrence of an internal short circuit due to foreign. matter, or the penetration of the battery by sharp objects such as nails and screws, or excessive deformation of the battery by external force.

However, since the heat resistance temperature thereof is in a range of about 120° C. to about 160° C., heat resistance properties may be insufficient.

Thus, the performance of the battery may be adversely affected.

In particular, since the edges have more irregular surfaces than the inside when coating the polymer electrolyte, the edges are not evenly coated.

Thus, a short circuit is likely to occur.

Also, when upper and lower layers of The electrodes are even slightly misaligned with each other while stacking the electrodes, a short circuit between the cathode and the anode may occur.

However, such a winding operation of the insulation tape may be highly complicated, and in the case that the insulation tape is wrapped to a slightly extended length from the upper end of the current collector to the bottom, the above wrapped portion may cause an increase in the thickness of the electrode assembly.

Furthermore, the wrapped portion may be easily loosened during the bending of the electrode tab.

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